1. Field of the Invention
The present invention relates to a method of supplying and discharging pressurized fluid and, for example, it concerns a method suitable for supplying and discharging pressurized oil to a work pallet which is detachably fixed to a table of a machine tool.
2. Explanation of Related Art
A conventional example of the pressurized fluid supply and discharge method of this kind was disclosed in Japanese Patent Publication No. 3-47975. The conventional technique is arranged as follows.
When connecting a quick coupler which comprises a socket and a plug, an air cylinder advances the socket toward the plug to thereby first seal a leading end of the socket and a leading end of the plug. Then a first stop member within the socket is brought into butting contact with a second stop member within the plug, thereby forcedly opening a first check member within the socket and a second check member within the plug. And the air cylinder exerts a pushing force, which holds the socket connected to the plug. In that state, pressurized oil is supplied from a first supply and discharge port of the socket to a second supply and discharge port of the plug.
The conventional technique has the following problem.
In the foregoing connected state, the first check member of the socket is always kept open as well as the second check member of the plug. Therefore, on stopping the pressurized oil supply to the first supply and discharge port, the pressurized oil at the second supply and discharge port is discharged to an exterior area through the first supply and discharge port. In consequence, in order for the second supply and discharge port to hold its pressure even after the socket has been separated from the plug, the socket has to be separated from the plug with the pressurized oil supplied to the first supply and discharge port. This results in easy leakage of the pressurized oil from the sealed portion of the leading ends of the socket and of the plug.
The present invention aims at making it possible to prevent the leakage of pressurized fluid when separating a coupler.
In order to accomplish the above aim, for example, as shown in FIGS. 1 to 4, the present invention provides a method which connects a first coupling 21 fixed to a first block 1, to a second coupling 22 secured to a second block 2 and separates from each other, thereby supplying and discharging pressurized fluid between a first supply and discharge port 51 of the first block 1 and a second supply and discharge port 78 of the second block 2. The method comprises the following steps.
When supplying the pressurized fluid from the first supply and discharge port 51 to the second supply and discharge port 78, first, the first block 1 and the second block 2 are brought closer to each other, thereby hermetically communicating a first flow passage 44 within the first coupling 21 with a second flow passage 66 within the second coupling 22. And a first stop member 45 within the first flow passage 44 is brought into butting contact with a second stop member 67 within the second flow passage 66. A contact gap (B) is formed between the second stop member 67 in that butting contact state and a check member 72 within the second coupling 22. Next, the second block 2 is fixed to the first block 1 by a locking means 3 under a locking condition (X). In that state, pressurized fluid is supplied to the first supply and discharge port 51, thereby supplying the pressurized fluid to the second supply and discharge port 78 via the first flow passage 44, the second flow passage 66, an interior area of a check valve seat 71 and a check valve chamber 70. Subsequently, a resilient member 73 exerts an urging force which brings the check member 72 into closing contact with the check valve seat 71. Thereafter, the pressurized fluid at the first supply and discharge port 51 is discharged to an exterior area. And the locking means 3 is switched over from the locking condition (X) to an unlocking condition (Y), thereby separating the first block 1 and the second block 2 from each other.
Contrary to the above, when discharging the pressurized fluid supplied to the second supply and discharge port 78, to the first supply and discharge port 51, first, the first block 1 and the second block 2 are brought closer to each other, thereby hermetically communicating the first flow passage 44 with the second flow passage 66 and bringing the first stop member 45 into butting contact with the second stop member 67. Then the second block 2 is fixed to the first block 1 by the locking means 3 under the locking condition (X). In that state, an actuation means 59 separates the check member 72 from the check valve seat 71 through the first stop member 45 and the second stop member 67 in the mentioned order, thereby discharging the pressurized fluid at the second supply and discharge port 78 to the first supply and discharge port 51 via the check valve chamber 70, the interior area of the check valve seat 71, the second flow passage 66 and the first flow passage 44. Thereafter, the locking means 3 is switched over from the locking condition (X) to the unlocking condition (Y), thereby separating the first block 1 and the second block 2 from each other.
The present invention offers the following advantages.
After the pressurized fluid has been supplied from the first supply and discharge port of the first block to the second supply and discharge port of the second block, the check member within the second coupling is brought into closing contact with the check valve seat by the resilient member. Therefore, even if the pressurized fluid at the first supply and discharge port is discharged to the exterior area, it is possible to retain a pressure of the second supply and discharge port at a predetermined one. And the first coupling and the second coupling are separated from each other in a state where the first flow passage and the second flow passage have lost their pressures by discharging the pressurized fluid at the first supply and discharge port to the exterior area. Therefore, it is possible to prevent the leakage of the pressurized fluid upon that separation.
Besides, at the time of the foregoing separation, the first flow passage has lost its pressure. Accordingly, the pressurized fluid does not make its pressure act from the first coupling to the second coupling, so that there is no need for receiving a force exerted by the pressurized fluid.
The present invention includes the following method.
The actuation means 59 comprises a piston 54 which faces the first stop member 45, and an actuation chamber 56. And when the pressurized fluid is supplied from the first supply and discharge port 51 to the second supply and discharge port 78, first, pressurized fluid for forced valve-opening is supplied to the actuation chamber 56. This separates the check member 72 from the check valve seat 71 via the piston 54, the first stop member 45 and the second stop member 67. The pressurized fluid supplied to the first supply and discharge port 51 is supplied to the second supply and discharge port 78. Next, the pressurized fluid for forced valve-opening within the actuation chamber 56 is discharged to an exterior area. Thereafter, the pressurized fluid at the first supply and discharge port 51 is discharged to the exterior area.
The above-mentioned invention produces the following function and advantages.
On supplying the pressurized fluid from the first supply and discharge port to the second supply and discharge port, the check member is forcedly opened, thereby being able to secure a large opening gap over the entire term for supplying the pressurized fluid. This makes it possible to carry out the supply of the pressurized fluid for a short period of time. In addition, the forcedly opened check member can inhibit the chattering caused by pressure pulsation, which results in the possibility of preventing a valve face or a valve seat from being damaged. Thus it is possible to keep the checking performance in a good condition over a long period of time.
Besides, since the foregoing advantage can be achieved by utilizing the above-mentioned existing actuation means, there is no need for adding a new construction to result in being able to put the present invention into practice with a simple construction inexpensively.